Magnetic tunnel transistor with high magnetocurrent

Abstract

A magnetic tunnel transistor (MTT) having a pinned layer that has no antiferromagnetic material in an active area of the sensor. The MTT can include a layer of antiferromagnetic material that is exchange coupled with the pinned layer in an area outside of the active area of me sensor, such as outside the track-width, beyond the stripe height, or both outside the track-width and beyond the stripe height. The pinned layer can also be pinned without any exchange coupling at all. In that case, pinning can be assisted by shape enhanced magnetic anisotropy, by extending the pinned layer beyond the stripe height.

Description

RELATED INVENTIONS[0001]This is a Continuation in Part application of commonly assigned, U.S. patent application Ser. No. 11 / 187,665 entitled, MAGNETIC TUNNEL TRANSISTOR WITH HIGH MAGNETOCURRENT AND STRONGER PINNING, filed on Jul. 22, 2005 now U.S. Pat. No. 7,372,674, which is incorporated herein by reference as if fully set forth herein.FIELD OF THE INVENTION[0002]The present invention relates to magnetic tunnel transistors and more particularly to a magnetic tunnel transistor having a pinned layer structure formed directly on a GaAs base, resulting in improved pinned layer pinning and increased magnetocurrent.BACKGROUND OF THE INVENTION[0003]The heart of a computer's long term memory is an assembly that is referred to as a magnetic disk drive. The magnetic disk drive includes a rotating magnetic disk, write and read heads that are suspended by a suspension arm adjacent to a surface of the rotating magnetic disk and an actuator that swings the suspension arm to place the read and w...

AI Technical Summary

Benefits of technology

[0013]The present invention provides a magnetic tunnel transistor (MTT) having improved performance and robust performance. An MTT according to the present invention includes an emitter, base and collector. The base includes a free layer, pinned layer and a non-magnetic spacer sandwiched between the free and pinned layer. The emitter and base are separated by a thin, electrically insulating barrier layer. The magnetic tunnel transistor has stripe height that is measured from the ABS to the edge of the free layer furthest from the ABS. The pinned layer can extend significantly beyond this stripe height and is exchange coupled to a layer of antiferromagnetic material (AFM) layer in a region outside of the active area of the sensor.

[0015]Having an AFM layer in the active region of the sensor significantly degrades performance by scattering electrons and greatly reducing the number of hot electrons passing through the barrier transistor. However, strong pinned layer pinning is needed to maintain robustness.

[0017]In addition, the collector can be removed from the gap, by recessing the collector from the ABS and forming the bottom electrode so that it contacts the base, and not the collector in this recessed region. This greatly reduces the gap thickness which increases data density when the MTT is used as a sensor in a magnetic data recording device.

Problems solved by technology

Having an AFM layer in the active region of the sensor significantly degrades performance by scattering electrons and greatly reducing the number of hot electrons passing through the barrier transistor.

Images